The vice mayor of Shanghai in charge of its experimental free trade zone is being investigated for suspected "serious breaches of discipline", the antigraft watchdog of the ruling Communist Party said on Tuesday, using its usual euphemism for corruption.

The Central Commission for Discipline Inspection gave no further details of the investigation into Vice Mayor Ai Baojun, the most senior official from China's finance hub to be swept up in an anti-corruption campaign launched by President Xi Jinping after taking power some three years ago.

It was not possible to reach Ai for comment and unclear if he has a lawyer.

Ai, a native of the northeastern province of Liaoning, became a vice mayor of Shanghai in December 2007, according to an official online biography.

Ai has headed the committee that runs the Shanghai Free Trade Zone since its launch in September 2013, as part of a government effort to test a more open and streamlined environment for foreign firms to do business, along with the relaxation of policies for several service sectors.

He was also a director of the Shanghai International Tourism and Resorts Zone, where a new Disney theme park is being developed, the Shanghai Daily said.

Shanghai's party boss Han Zheng called the news "heartbreaking" but said he supported the investigation and a zero-tolerance policy on corruption, the newspaper reported.

"Every Party member and leader should reflect deeply on and learn from the case and take it as a grave warning. Government officials must be role models and regulate themselves, their relatives and staff," the newspaper quoted Han as telling a meeting of the city's party committee on the issue.

Before entering politics, Ai was a university professor and then worked his way up to the position of general manager of China's second-largest steel producer, Baosteel Group.

He is the most senior Shanghai official to be investigated for corruption since the city's then-Communist Party chief Chen Liangyu was jailed for 18 years for graft in 2008.

Dai Haibo, a deputy secretary of the Shanghai government and former deputy head of the free trade zone, was stripped of his post this year, following an investigation by the anti-corruption watchdog.